Carbon Dioxide

Carbon dioxide released by man near ground level is concentrated in fairly small volumes and is heavier than air and sinks in air relatively quickly rather than rising up to the upper atmosphere to become a so-called greenhouse gas in the upper atmosphere. While sinking, this carbon dioxide stratifies from air; after sinking and stratifying, it tends to remain close to the ground. The carbon dioxidecan then dissolve in soil water or alternatively it may find its way down to low-lying water bodies or down to ocean level where it readily mixes and dissolves in water or reacts with water to form weak carbonic acid. Carbon dioxideis also removed immediately from the lower atmosphere by rainfall.

Direct measurements of the concentration of carbon dioxide in the atmosphere, as shown by the Keeling Curve, have been performed continuously only since 1958 at Mauna Loa, Hawaii, unlike carbon dioxide measurements before 1958, shown in red in the graph displayed here and in non-green in this chart. In the nineteenth and twentieth centuries A.D., many direct measurements of the atmospheric concentration of carbon dioxide were higher than present-day carbon dioxide measurements and there was no runaway greenhouse-gas global warming effect.

Certain extra mechanisms, not yet described publicly, remove carbon dioxide from the atmosphere which results in the so-called “missing carbon sink”. These extra mechanisms, removing carbon dioxide from the atmosphere, need to be adequately explained and understood if the extent of human impact on the global carbon cycle is to be acceptably assessed and reliably predicted. The missing carbon sink can be explained by increased carbon fixation, such as that which occurs during increased plant growth. When plants grow, carbon in carbon dioxide becomes carbon in plant material such as cellulose and starch. After plants die, carbon from decomposed plant material is released into soil and in between layers of sediments.

Compared to carbon dioxide emitted near ground level by man, carbon dioxide, emitted by aircraft just above the tropopause, spends a lot more time sinking in the atmosphere because of higher wind speeds at higher altitudes in addition to the greater distances to sink. Carbon dioxide emitted by jet aircraft does not sink straight down without any horizontal displacement due to winds and natural diffusion.

Carbon dioxide is constantly being added by jet aircraft to the atmosphere just above the tropopause, the boundary region between the troposphere and the stratosphere. Jet aircraft fly above the troposphere to avoid turbulence. The troposphere ranges in height from 7 km at the poles to 16 km at the equator.

In this reply, meteorologist Wendell Bechtold wrote: “120 Kt winds at 12,000 feet are rare, but not unheard of. An unusually strong mid-level pressure system might produce such winds over a small region. But the upper-level jet stream, usually found above 18,000 feet can reach speeds above 100 mph regularly, and at altitudes of 30,000 feet, 200 mph wind velocities occasionally occur. The ‘average’ jet stream windspeed in wintertime over the northern hemisphere is probably 110-140 kts, at altitudes of 20 to 40 thousand feet.”

Carbon dioxide, emitted near ground level by man, is emitted where the winds are either much slower than higher-altitude winds or non-existent. Local ground weather is mostly not windy.

Hawaii is a major destination point for aircraft approaching and a major point source for aircraft leaving. The Mauna Loa data for the Keeling curve is obtained at an altitude of 3.4 km. Aircraft approaching and leaving Hawaii fly at altitudes greater than 3.4 km.

State of Hawaii Department of Transportation air traffic statistics for the calendar years 1994 through 2005 show that Hilo International Airport alone had 108,462 takeoffs and landings in 2005 compared to 86,292 takeoffs and landings in 1994. This is a 25% increase over ten years. Graphs of atmospheric carbon dioxide concentrations measured at Mauna Loa Observatory also show an increase over this same time period.

World air travel by distance from 1950 to 2003 is listed in this article by Zoë Chafe, citing data from the International Civil Aviation Organization (ICAO). For 1960, the world air travel distance number given is 109 billion passenger-kilometers. For 2003, the world air travel distance number given is 2,992 billion passenger-kilometers.

Replacing most present-day air travel with Earth-surface travel would have a measurable effect on reducing carbon dioxide concentrations in the atmosphere, but may do little to reduce the overall greenhouse effect because water in the atmosphere causes, by far, most of the greenhouse effect.

The mass of water in the atmosphere is about 1.3 × 10¹⁶ kg. The mass of carbon dioxide in the atmosphere is about 2.5 × 10¹⁵ kg. The molar mass of water is 18.02 g/mol. The molar mass of carbon dioxide is 44.01 g/mol. There are more than 12 times as many water molecules in the atmosphere than carbon dioxide molecules in the atmosphere. Additionally, the water molecule is polar and the carbon dioxide molecule is non-polar, so a water molecule absorbs more radiation than a carbon dioxide molecule.

“The IPCC has always overstated the importance of carbon dioxide as a greenhouse gas and under-estimated the importance of water vapour”, according to Warwick Hughes here.

Warming increases cloud cover. Increasing cloud cover causes cooling. Cooling decreases cloud cover. Decreasing cloud cover causes warming.

Personally, I have not noticed any local long-term climate warming trend. Globally, measurements show cooling of the oceans since 2003. The Antarctic ice area has increased from 1979 to 2009. The Antarctic ice volume is about 90% of the world’s ice volume, according to Table 6.1 in Chapter 6 of the Earth Observing System (EOS) Science Plan.

“The United States and Global Data Bases are Seriously Contaminated by urbanization for which NO ADJUSTMENTS are made. ... The United States USHCN version 2, the global NOAA GHCN relied on by the CCSP and the Hadley global temperatures are NOT adjusted for UHI contamination”, according to Joseph D'Aleo in Urban Heat Island Contamination. This document states: “It is not out of the realm of possibility that most of the twentieth century warming was urban heat islands”.

“When CO₂ enters the ocean, it participates in a series of reactions which are locally in equilibrium:

Solution: CO₂(atmospheric) <=> CO₂(dissolved)

Conversion to carbonic acid: CO₂(dissolved) + H₂O <=> H₂CO₃

First ionization: H₂CO₃ <=> H⁺ + HCO₃^- (bicarbonate ion)

Second ionization: HCO₃^- <=> H⁺ + CO₃^-- (carbonate ion)

... In the oceans, carbonate can combine with calcium to form limestone (calcium carbonate, CaCO₃, with silica), which precipitates to the ocean floor”, according to Wikipedia's Carbon cycle article.

“CO₂ + H₂O <=> H₂CO₃ <=> H⁺ + HCO₃^- <=> H⁺ + H⁺ + CO₃^2-

Add more CO₂ at the left and the equilibrium balance is driven to the right – liberating more carbonate, which can combine with the superabundant calcium ions to form calcium carbonate. … By elementary chemistry, adding CO₂ to a CO₂/carbonate equilibrium will always drive the reaction towards the production of more carbonate, irrespective of any associated reduction in pH arising from the shift in equilibrium itself”, according to this blog.

In this article, Dr J Floor Anthoni wrote: “If the amount of CO₂ in the atmosphere rises, then more of it will dissolve in the water, working all the way through the chemical reactions, to an increase in acidity and an increase in carbonate CO₃”; and, “... the sea has a vast oversupply of calcium. It is difficult therefore to accept that decalcification could be a problem as CO₃ increases. To the contrary, it should be of benefit to calcifying organisms. Thus the more CO₂, the more limestone is deposited. This has also been borne out by measurements (Budyko 1977)”.

According to Wikipedia's Carbon cycle article, the “calcium comes from the weathering of calcium-silicate rocks, which causes the silicon in the rocks to combine with oxygen to form sand or quartz (silicon dioxide), leaving calcium ions available to form limestone[6]”.

Shallow ocean water is normally saturated with CO₃^2- carbonate ions. Carbon dioxide entering the ocean causes the local ocean concentrations of CO₃^2- to temporarily increase, resulting in supersaturated CO₃^2- carbonate ions. The supersaturated CO₃^2- carbonate ions need to precipitate to return the water to normal saturated CO₃^2- conditions.

A supersaturated CO₃^2- carbonate ion precipitates by combining with a Ca²⁺ calcium ion liberated from a calcium-silicate rock. When the calcium Ca²⁺ cation is liberated from the calcium-silicate rock, an oxygen O^2- anion is also liberated. The oxygen O^2- anion then reacts with the two H⁺cations that were dissociated with each CO₃^2- carbonate ion.

So the concentrations, of the three far right ions in the equilibrium equation, return to their concentrations before the carbon dioxide entered the ocean. With the concentrations of the three far right ions in the equilibrium equation returning to their original concentrations, the concentrations of dissolved CO₂, H₂CO₃, H⁺, and HCO₃^- also return to their original concentrations. In this manner, the “increase in acidity”, when carbon dioxideenters the ocean, is neutralized.

With carbon dioxide constantly being added to the ocean from the atmosphere, and with carbonate ions constantly precipitating out by combining with calcium or magnesium ions, the above equilibrium reaction actually becomes part of a one-way irreversible reaction for each one individual participating molecule, except for water:

==> CO_2(aq) + H₂O ==> H₂CO₃ ==> H⁺ + HCO₃^- ==> H⁺ + H⁺ + CO₃^2- ==>

The overall concentrations, however, remain at or near equilibrium concentrations. At equilibrium conditions, for each carbon dioxide molecule that enters in, one carbonate ion precipitates out.

Irreversible reactions, for the calcium-silicate rocks grossularite, andradite, and uvarovite, produce alumina, hematite, and eskolaite, respectively.

Ca₃Al₂(SiO₄)₃ + 3 CO₂ + 3 H₂O ==> Al₂O₃ + 3 CaCO₃ + 3 SiO₂ + 3 H₂O

Ca₃Fe₂(SiO₄)₃ + 3 CO₂ + 3 H₂O ==> Fe₂O₃ + 3 CaCO₃ + 3 SiO₂ + 3 H₂O

Ca₃Cr₂(SiO₄)₃ + 3 CO₂ + 3 H₂O ==> Cr₂O₃ + 3 CaCO₃ + 3 SiO₂ + 3 H₂O

The irreversible silicate-carbonate reactions, summarized as CaSiO₃ + CO₂ + H₂O ==> CaCO₃ + SiO₂ + H₂O, have no net increase in acidity when limestone and silica precipitate as a result of adding carbon dioxide. Deep in the Earth, calcium carbonate may break down, into carbon dioxide and into calcium oxide, upon heating to above 840°C, but volcanoes only emit about 0.2 gigatonnes of carbon dioxide per year, according to various claims. Therefore, man-made carbon dioxide emissions to the atmosphere do not, and will not, cause ocean acidification.

Email concerning this web page may be sent to David Wozney at dpwozney@ocii.com.